Comparative metabolism of linamarin and amygdalin in hamsters.

Abstract

Rates of cyanide liberation resulting from hydrolysis of the cyanogenic glycosides linamarin, amygdalin and prunasin by a crude beta-glucosidase prepared from hamster caecum were studied in vitro. In addition, hamster blood cyanide and thiocyanate concentrations were determined at 0.5, 1, 2, 3 and 4 hr after an oral dose of 0.44 mmol linamarin or amygdalin/kg body weight. Plots of cyanide liberated v. time for linamarin and prunasin yielded straight lines. A similar plot for amygdalin was curvilinear, with the rate of cyanide release increasing with time. At 10(-3) M substrate concentrations, the average rates of hydrolysis of prunasin, amygdalin and linamarin were 1.39, 0.57 and 0.13 nmol/min/mg protein, respectively. Lineweaver-Burk plots yielded apparent Km and Vmax values of 3.63 X 10(-5) M and 0.35 nmol/min/mg protein, respectively, for amygdalin, and 7.33 X 10(-3) M and 1.04 nmol/min/mg protein, respectively, for linamarin. Blood cyanide concentrations following amygdalin treatment reached their highest level (130 nmol/ml) 1 hr after dosing and remained elevated until 3 hr after treatment. Blood cyanide concentrations following linamarin treatment reached their highest level (116 nmol/ml) after 3 hr and then declined immediately. Area under the blood cyanide concentration-time curve was 395 nmol-hr/ml for amygdalin and 318 nmol-hr/ml for linamarin. The results suggest a faster rate of enzymatic hydrolysis and cyanide absorption for amygdalin than for linamarin.

• Authors: R A Frakes, R P Sharma, C C Willhite
• Journal: Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association (Food Chem Toxicol) Vol. 24 Issue 5 Pg. 417-20 (May 1986) ISSN: 0278-6915 [Print] England
• PMID: 3744195 (Publication Type: Comparative Study, Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Cyanides
• Nitriles
• prunasin
• Amygdalin
• linamarin

Topics

• Amygdalin (metabolism)
• Animals
• Cricetinae
• Cyanides (metabolism)
• Female
• Hydrolysis
• Kinetics
• Mesocricetus
• Nitriles (metabolism)